1. Field of the Invention
The present invention relates to a hot material marking apparatus for marking identification signs onto hot materials such as slabs and blooms being conveyed on a conveying course in a blooming mill or a continuous iron foundry.
2. Description of the Prior Art
For identification in the succeeding process, a hot material is required to be marked thereon numerals and letters of about ten figures.
Despite that hot materials have an ambient temperature ranging from several hundred to one thousand and several hundred degree C, it is possible to carry out reliable marking by use of a coating composition having high heat resistance and good adhesiveness which is made of a ceramic material, without the possibility of disappearing, or falling off after cooling.
As a marking apparatus of using the above coating composition, there has been proposed a marking apparatus constructed such that: repeated use type stencils made of elongated thin metal plates are prepared in a number equal to the number of the figures to be marked, which are each penetratingly provided therein with a necessary numeral or letter and each connectd at opposite end portions thereof in the longitudinal direction to each other so as to be formed into a ring; the stencils thus prepared are loosely coupled onto a cylindrical drum to be rotatable on the axis of the drum; and nozzles provided in the drum are adapted to inject the coating composition onto a hot material through perforations formed in the stencils.
However, with the proposed marking apparatus, the coating composition adheres to portions of the perforations adjacent to the stencils during use and are solidified due to the high temperature of the hot material, the areas of the perforations are substantially decreased to result in unclear marking, repeated use of the stencils become difficult, considerable time is required for repairing and the like, and extra labor is needed for continuous work. Additionally, there has been proposed a marking apparatus in which a large amount of cleaning water is used to prevent the coating composition from being adhered, but in reality, it was impossible to achieve the purpose.
Despite that coating compositions withstanding the adverse conditions caused by hot materials have been developed, the marking has been really carried out after the hot materials have been cooled because there has been no practicable marking method and apparatus therefor.